Machine for grinding the teeth of gear wheels



Nov. 19, 1946, A. H. ORCUTT 2,411,456

MACHINE FOR GRINDING THE TEETH OF GEAR WHEELS Nov. 19, I946. A, HORCUTT2,411,456

MACHINE FOR GRINDING THE TEETH OF GEAR WHEELS Filed May 10, 1945 8Sheets-Sheet 2 Nov. 19, 1946.

MACHINE FOR A. H. ORCUTT 2,411,456

GRINDING THE TEE'fH 0F GEAR WHEELS Filed May 10, 1945 8 Sheets-Sheet 5Jzz v era-2501 I .HO 6% Nov. 19, 1946. A. H. o cu r'r 2,411,456

MACHINE FOR GRINDING THE TEETH OF GEAR WHEELS Filed May 10, l945 8Sheets-Sheet 4 Nov. 19, 1946. A. H. ORCUTT MACHINE FOR GRINDING THETEETH OF GEAR WHEELS Filed May 10, 1945 8 Sheets-Sheet 5 1122/21 elviol4, H Orawifi Nov, 19, 1946. H. ORCUTT MACHINE FOR GRINDING THE TEETH OFGEAR WHEELS Filed May 10, 1945 8 Sheets-Sheet 6 Nov. 19, 1946. AT ORCUTT2,411,456

MACHINE FOR GRINDING THE TEETH OF GEAR WHEELS Filed May 10, 1945 8Sheets-Sheet 7 FEE Nov. 19, 1946. ORCUTT MACHINE FOR GRINDING THE TEETH0F GEAR WHEELS 8 Sheets-Sheet 8 Filed May 10, 1945 Patented Nov. 19,1946 MACHINE FOR GRINDING THE TEETH OF GEAR WHEELS Arthur HitchcockOrcutt, Shirley, near Birmingham, England, assignor to The Gear GrindingCompany Limited, Shirley, near Birmingham,

England Application May 10, 1345, Serial No. 593,078 In Great BritainMay 5, 1944 12 Claims.

This invention relates to machines for grinding the teeth of gearwheels, of the kind in which a formed grinding wheel is reciprocatedbetween the tooth surfaces, and the toothed wheel is intermittentlyrotated to bring successive tooth faces under the action of the grindingwheel, the latter being trimmed periodically to maintain its form, Theobject of the present invention is to enable the feed movements of theworkpiece relatively to the grinding wheel, and also the determining ofthe wheel trimming periods, to be effected automatically.

The invention comprises the combination with a headstock, a side movablevertically in the headstock, a workspindle carried by the slide, amanually operable screw for moving the slide in the headstock, and anindex-plate carried by the work spindle of an intermittently operablefeeding mechanism for imparting feed movements to the slideindependently of the said screw, means consisting in part of anelectromagnet for actuating the feeding mechanism, and means responsiveto rotational movements of the work spindle for controlling the saidelectromagne-t.

The invention also comprises the combination with the feeding mechanism,of electrical contact devices for determining the grinding wheeltrimming periods.

In the accompanying sheets of explanatory drawings- Figures 1 and 2 arerespectively side and end elevations of a known form of gear wheelgrinding machine having the invention applied thereto.

Figure 3 is a sectional side elevation and Fig ure 4 a sectional endelevation of a mechanism embodying the invention.

Figure 5 is a plan illustrating the mechanism with portions broken awayto disclose certain of the electrical contact devices.

Figure 6 is a plan illustrating the mechanism for imparting feedmovements to the work piece.

Figures 7 and 8 are respectively sectional side elevations in planes atright angles to each other of the mechanisms shown in plan at Figures 5and 6.

Figures 9 and 10 are detail views of certain elements to be referred tohereafter.

To facilitate explanation of the invention, a brief description willfirst be given of the machine illustrated by Figures 1 and 2, the largerpart of this machine being already known. On the bed a is arranged aslide 1) which is adapted to be reciprocated horizontally on the bed a.The slide carries a rotary grinding Wheel c-the periphery of which isshaped to conform with the 2 adjacent flanks of a pair of wheel teeth.Associated with the headstock d is arranged a spindle e which carriesthe toothed wheel to be ground, the latter being herein referred to asthe work piece. The spindle e is carriedby a slide which is movablevertically between guides in the headstock. This movement can beefiected manually by a hand operable member f engaging a screw g.

Intermittent angular movements are given to the spindle e to bringsuccessive tooth spaces opposite the grinding wheel, and these movementsare imparted by a known mechanism which includes a peripherally notchedindex plate to be referred to again hereafter. Also on the bed of themachine is' arranged a known form of trimming mechanism for periodicallytruing the operative parts of the grinding wheel, this mechanism beingindicated generally by It in Figure 1. The mechanism forming the subjectof the present invention is arranged for the greater part in associationwith the headstock d.

Referring now to Figures 3 and 4 which illustrate the headstock d morefully, the work spindle e is carried as already stated by a slide 2'movable between guides in the headstock, and at the rear end of thespindle e is secured the peripherally notched index plate I. This plateis given intermittent angular movements by a known mechanism which formsno part of the present invention and which has been omitted from thedrawings to avoid undue complication. The source of motion of this plateis a shaft m (Figure 1) which serves to actuate a pawl engaging thenotches of the index plate, the pawl being located in the housing it(Figure 2) rdinarily the feed screw g is directly connected at one endto the slide 1', but for the purpose of my inventionit is attached to aconnecting piece 0 which'in turn is connected by a link 10 to aforked'crank arm q. The link is pivotally attached at its ends to thepiece 0 and the crank arm respectively. The crank arm is pivotallyattached to the slide 1' in the manner clearly shown in-Figure 4, andthe pivot axis of the crank arm is eccentric to the adjacent pivot axisof the connection between the link 10 and the crank arm q as is alsoclearly shown in Figure 4. The arrangement is such that the slide can beraised and lowered to any desired position by manual operation throughthe medium of member 1 and the screw 9. The member .1 is carried on theheadstock and consists in part of a nut engaging the screw. But the feedmovements are-hu parted to the slide by the crank arm independently ofthe screw through a range which is determined by the eccentricity of thetwo pivot axes above mentioned and which is made sufiicient to allow thework piece to be fed relatively to the grinding wheel by the amountcorresponding to the amount of material to be removed from the workpiece by the grinding wheel. The actuation of the crank arm is effectedautomatically in the manner which will now be described with particularreference to Figures 3, 4, 6, 7, and 8.

Alongside the headstock is mounted a housing 1" herein referred to asthe control box. In the control box is mounted a spindle s which at itsupper end has secured to it a dial t operable by a handle 6 (Figures 1,2 and 4) enabling the spindle s to be actuated by hand when required,and on th housing is secured a pointer u (Figures 1 and 2) for assistingthe user to set the dial to any desired position. On the spindle sissecured a pinion 22 which engages a slidable rack in one end of which ispivotally connected by a link to the crank arm q (Figure 3), enablingfeed motions to be imparted to the crank arm and thence to theworkpiece, either by hand or automatically. To efiect automaticactuation there is also secured to the spindle s a peripherally notcheddisc y (see Figure 6) and in association with this disc there ispivotally mounted in the control box an arm 2 which carries a pivotedpawl 3 loaded by a tension spring 4 which tends to hold one end of thepawl in engagement with the disc y. In addition there is pivoted in thecontrol box a retaining pawl 5 which is loaded by a blade spring 'i, thepurpose of this pawl being to prevent reverse rotation of the notcheddisc. Toenable both pawls to be put out of action when it is desired tobe able to rotate the disc by hand in either direction, a rotatable cam8 (Figure 6) is arranged in the control box in association with a pairof adjacent ends of the two pawls, this cam being rotatable by a handle9 (Figure 5). Automatic actuation of the arm 2 is effected in onedirection by a solenoid H3 and in the other direction by a spring Ii,The arm is connected to the movable core of the solenoid by a link 12,and this link is also connected to a tube E3 which can slide on a fixedguide bar M, the spring H being located within this tube as shown inFigure 6. The solenoid serves to effect retractive idle movements of thearm 2 and pawl 3 relatively to the notched disc y, and the spring itserves to impart the required feed movements to the disc y through thesaid arm and pawl. An adjustable stop l5 carried by the control boxserves to limit the operative movements of the arm.

The control of the supply of electric current i from any convenientsource to the solenoid is effected by the index plate I. On this plateis secured a striker it, which at the end of each complete rotation ofthe index plate, engages a lever I1 (Figures? and 9) and by lifting thislever causes it to raise a plunger l3 which lifts a movable contactpiece EQinto contact with a pair of resilient contacts 20 which may beloaded by springs 2! (Figure 9), so closing the solenoid circuit. Theeffect of this is to bring the solenoid It into action, causing the arm2 and pawl 3 to be retracted against the action of the spring I I, and

to hold the said parts in their retracted position. When the index plateI begins its next rotation the striker I6 leaves the lever I! and allowsthe contact pieces to resume their initial positions, thereby causingthe solenoid circuit to be reopened. Whereupon the spring ll imparts afeed movement to the work piece, the above described action beingrepeated after each complete rotation of the index plate until thegrinding operation has been completed.

The angular movement given to disc y in each action is constant, but thefeed movement given to the slide 2' progressively diminishes as thecrank arm q approaches the central or vertical position, Consequently atthe commencement of a grinding operation on the work piece the feedmovements are relatively coarse, and they become progressively finertowards the completion of the grinding operation. The total step-bystepmovement required to be given to the disc 3 for moving the crank arm qthroughout its range of movement (which corresponds to the total feedmovement to be given to the slide 2' for a given work piece) is usuallya little less than one revolution.

During the grinding operation it is necessary to trim the grinding wheelat appropriate intervals, and to enable these periods to be determinedautomatically. we provide on the dial 1? of the control box, a series ofsuitably placed and externally projecting radial striking pieces 23(Figures 5 and 7). These are not equally spaced, but are so disposedthat the time intervals between successive trimming actions are longerduring the initial stages of the grinding operation when what may betermed coarse grinding occurs, than in the later stages when the fine orfinishing grinding occurs. The striking pieces 23 are brought intoaction successively during the rotation of the dial t by the spindle stowhich is secured the notched disc y above described. The particularmachine to which the invention is shown applied is ordinarily fittedwith a mechanism controlled by a hand lever 24 (Figure 1) by which thgrinding action can be temporarily arrested. The slide b is caused to beretracted so as to bring the grinding'wheel c to the trimming mechanismh by a further lever (not shown). In association with this mechanism wearrange any convenient electromagnetic means such as a solenoid (notshown) which when excited serves to perform the same function as thesaid levers, and

this solenoid is arranged in a circuit which is controlled by a switchoperable'by the strikers 23. The switch (see Figure 5) comprises a pairof contacts 25, 26 and a pivoted contact member '2? loaded by a spring28 which tends to hold the part 27 on the contact The contact member 21is movable in opposition to the spring on to the contact 26 through aplunger 29 by any one of the strikers 23. The contact 25 is in serieswith the circuit containing the feed solenoid in above described, andthe contact 26 is in the circuit of the solenoid above mentionedassociated with the controlling means of the trimming mechanism. Whenany of the strikers 23 reaches the plunger 29 it causes the latter tomove the member 21 so as to open the circuit of thesolenoid It! (andthereby put the feed mechanism out of action) and close the circuit ofthe other solenoid through the contact 26. This latter solenoid nowperforms the function ordinarily effected 'byLone. of

the above mentioned levers and the slide biis caused to move to thewheel trimming position. The trimming operation is then performed in theusual manner either under. the control of the attendant orautomatically, this operation the attendant means such as a push buttonswitch on the control panel 3d. But it is also necessary at the sametime to bring the feed solenoid into action again by restoring theswitch (25.- 26.- 21) to its initial and on completion of restarts thernachine in the usual manner by actuationcf the usual condition. Toenable this to be effected, I mount the plunger 29 on a pivoted arm 3|(Figures 5 and loaded by a spring 32, and the arm 3| is connected by alink 33 to the core 3 of a solenoid 35 situated in the control box. Thecircuit of this solenoid is controlled by a switch 31 (Figure 1) whichis operable by a tappet 38 on the slide 1). When th slide returns in theusual manner to the working position after the'wheel has been trimmedthe tappet 38 knocks the switch 31 over from one of its limit positionsto the other, and during this movement the circuit of the solenoid 35 ismomentarily closed causing the solenoid core to pull the arm 3! to theleft (Figures 5 and 10) and so carry the plunger 29 away from thestriker with which it was previously in contact. The part 21 now returnsunder the action of its spring to the contact 23 and so reestablishesthe circuit of the feed solenoid Ill. The previously described grindingoperation on the work piece is now resumed until the next striker 23comes into action and causes the grinding wheel to be again moved to thetrimming position, theprocess being repeated until the grindingoperation is completed.

In order that the attendant may be warned when the grinding operation isapproaching completion, I arrange in association with the dial t anotherswitch. This is located within the dial (see Figures5 and '7) and itcomprises a pair of contacts 40, M, and a pivoted contact member 42loaded by a spring 43. Also to the inside of the dial are secured atappropriate positions a pair of strikers M, 45. The striker 44 extendsbeyond the inner periphery 46 of the dial t and the striker 45 has arecessed inner end as shown. The member 42 is operable by a plunger 41which bears at one end against the said periphery 46 and at the otherend against the member 42. When the dial t reaches the position at whichthe final trimming operation is to be effected the striker 44 causes theplunger 41 to move the member 42 on to the contact 40. This closes acircuit containing any convenient warning device such as a lamp whichannounces to the attendant that the final trimming stage has beenreached. When the last striker 23 comes into action the striker 45allows the plunger 41 to move, so that the spring 43 can move the member42 onto the contact M. This closes a circuit containing another warningdevice such as a lamp which announces that the grinding operation iscompleted. At the same time the last striker 23 causes the slide b to beretracted to the trimming position in readiness for commencement ofoperations on the next work piece to be inserted in the machine. Beforethe operations above described are repeated on the next work piece, theattendant by means of the handle 6 on the dial 13, turns the dial backto its initial position which is determined by the abutment of a stop 50on the dial against a fixed stop 5| situated adjacent to the part 3!,the stop 5! serving also to support the said part 31 in its normalposition under the pressure of the spring 32.

By this invention the feed movements of the machine, and the determiningof the grinding Wheel trimming periods are effected automatically in asimple and satisfactory manner, enabling increased output and greateruniformity of quality to be obtained from machines of the kind specifiedas compared with earlier machines which have been under the sole controlof the attendant.

Having thus described my invention what I ating the feeding mechanism,and means respon sive to rotational movements of the work spindle forcontrolling the said electromagnet.

2. In a gear wheel grinding machine as claimed in claim 1, thecombination with the feeding mechanism of electrical contact devices fordetermining the grinding wheel trimming periods.

3. In a gear wheel grinding machine as claimed in claim 1, thecombination with the slide of a crank arm in pivotal connection with theslide, a link having one end in pivotal connection with the crank arm,the axes of the two said connections being eccentric with respect toeach other, and means effecting pivotal connection. between the otherend of the link and the screw.

4. In a gear wheel grinding machine having the features claimed in claim1, the combination of a crank arm in pivotal connection with the slide,a link having one end in pivotal. connection with the crank arm, theaxis of the two connections being eccentric with respect to each other,means for effecting pivotal connection between the other end of the linkand the screw, a peripherally notched disc, a pawl for impartingintermittent angular movements to the disc, means for transmittingmovements from the disc to the crank arm, a solenoid for moving the pawlin one direction, and a spring for moving the pawl in the oppositedirection.

5. In a gear wheel grinding machine having the features claimed in claim1, the combination of a crank arm in pivotal connection with the slide,a link having one end in pivotal connection with the crank arm, the axesof the two connections being eccentric with respect to each other, meansfor effecting pivotal connection between the other end of the link andthe screw, a peripherally notched disc, a pawl for impartingintermittent angular movements to the disc, means for transmittingmovements from the disc to the crank arm, a solenoid for moving the pawlin one direction, a spring for moving the pawl in the oppositedirection, a pinion associated with the disc, a slidable rack inengagement with the pinion, and means interconnecting the rack and crankarm.

6. In a gear wheel grinding machine having the features claimed in claim1, the combination of a crank arm in pivotal connection with the slide,a link having one end in pivotal connection with the crank arm, the axesof the two connections being eccentric with respect to each other, meansfor efiecting pivotal connection between the other end of the link andthe screw, a peripherally notched disc, a pawl for impartingintermittent angular movements to the disc, means for transmittingmovements from the disc to the crank arm, a solenoid for moving the pawlin one direction, a spring for moving the pawl in the oppositedirection, a pinion associated with the disc, a slidable rack inengagement with the pinion, means interconnecting the rack and crankarm,

and manually operable means for putting the pawl out of action.

7. In a gear wheel grinding machine having the features claimed in claim1, the combination of a crank arm in pivotal connection with the slide,a link having one end in pivotal connection with the crank arm, the axesof the two connections being eccentric with respect to each other, meansfor effecting pivotal connection between the other end of the link andthe screw, a peripherally notched disc, a pawl for impartingintermittent angular movements to the disc, means for transmittingmovements from the disc to the crank arm, a solenoid for moving thepawlin one direction, a spring for moving the pawl in the o ppositedirection, a solenoid controlling switch,

and means associated with the work spindle for closing the switch at theend of each complete rotation of the index plate. 1

8. In a gear wheel grinding machine having the features claimed in claim1, the combination "of a crank arm in pivotal connection with the slide,a link having one end in pivotal connection with the crank arm, the axesof the two connections being eccentric with respect to each other, meansfor effecting pivotal connection between the other end of the link andthe screw, a peripherally notched disc, a pawl for impartingintermittent angular movements to the disc, means for transmittingmovements from the disc to the crank arm, a solenoid for moving the pawlin one direction, a spring for moving the pawl in the oppositedirection, a Solenoid controlling switch, and a striker on the indexplate for closing the switch at the end of each complete rotation of theindex plate.

9. In a gear wheel grinding machine having the features claimed in claim1, the combination of a crank arm in pivotal connection with the slide,a'link having one end in pivotal connection with the crank arm, the axesof the two connections being eccentric with respect to each other,means'ior effecting pivotal connection between the other end of the linkand the screw, a peripherally notched disc, a pawl for impartingintermittent angul r movements to the disc, means for transmittingmovements from the'disc to the crank arm, a solenoid for moving the pawlin one direction, a spring for moving the pawl in the oppositedirection, a dial associated with the disc, a series of strikerscarried'by the dial, and a switch operable by the strikers fordetermining the trimming periods.

10. In a gear wheel grinding machine having the features claimed inclaim 1, the combination 4 of a crank arm in pivotal connection with theslide, a link having on end in pivotal connection with the crank arm,the axes of the two connections-being eccentric with respect to eachother, means for efiecting pivotal connection between the other end ofthe link and the screw, a peripherally notched disc, a pawl forimparting intermittent angular movements to the disc, means fortransmitting movements from the disc to the crank arm, a solenoid formoving the pawl in one direction, a spring for moving the pawlin theopposite direction, a dial associated with the disc, a series ofstrikers carried by the dial, and a switch operable oy'the strikers fordetermining the trimming periods, the switch being also adapted tocontrol the solenoid.

11. In a gear wheel grinding machine having the features claimed inclaim 1, the combination of a crank arm in pivotal connection with theslide, a link having one end in pivotal connection with the crank arm,the axes of the two connections being eccentric with respect to eachother, means for efiecting'pivotal connection between the other end ofthe link and the screw, a peripherally notched disc, a pawl forimparting intermittent angular movements from the disc to the crank arm,a solenoid for moving the pawlin one direction, a, spring for moving thepawl in the opposite direction, a dial associated with the disc, aseries of strikers carried by the dial, a switch operable by thestrikers for determining the trimming periods and controlling thesolenoid, a plunger for imparting movements from the strikers to theswitch, a pivoted member carrying the plunger, and a solenoid connnectedto the said member for retracting the plunger from the striker by whichthe plunger has previously been actuated.

12. In a gear wheel grinding machine having the features claimed inclaim 1, the combination of a crank arm in pivotal connection with theslide, a link having one end in pivotal connection with the crank arm,the axes of the two connections being eccentric with respect to eachother, means for effecting pivotal connection between the other end ofthe link and the screw,

a peripheraliy notched disc, a pawl for imparting intermittent angularmovements to the disc,

means for transmitting movements from the disc to the crank arm, asolenoid for moving the pawl in one direction, a spring for moving thepawl in the opposite direction, a dial associated with the disc, aseries of strikers carried by the dial,

a switch operable by the strikers for determining the trimming periods,another switch associated with the dial and adapted to control thecircuits of warning devices, and strikers on the dial for actuating thelatter switch when the grinding operation is approaching completion.

